DOG CLUTCH WITH A SENSOR FOR RECOGNIZING AN ENGAGED STATE

Abstract

A dog clutch having two clutch members provided with claws or teeth, one of which is movable, as well as a positioning device for engaging and disengaging the clutch by a positioning movement of the movable clutch member. In order to establish a proper engaging of the dog clutch, a sensor is arranged along the movement path of the movable clutch member, which detects the movement of the clutch member into the engaged state, while the clutch member is provided with an activating contour which, upon engaging the clutch, moves past the sensor, which is preferably an electromagnetic actuator for holding the movable clutch member in the disengaged state of the clutch.

Claims

1-9. (canceled)

10. A dog clutch, comprising: two clutch members provided with claws or teeth, one clutch member is movable, and a positioning device for engaging and disengaging the dog clutch by a positioning movement of the movable clutch member, wherein a sensor is arranged along the movement path of the movable clutch member, and detects the movement of the movable clutch member into an engaged state, wherein the movable clutch member is provided with an activating contour which, upon engaging the dog clutch, moves past the sensor.

11. The dog clutch according to claim 10, wherein the activating contour displaces an armature in a coil of the sensor and thereby induces a voltage in the coil.

12. The dog clutch according to claim 10, wherein the sensor is an electromagnetic actuator for holding the movable clutch member in a disengaged state of the dog clutch.

13. The dog clutch according to claim 12, wherein the sensor includes a pin, which stands in engagement with a locking contour of the movable clutch member when the dog clutch is disengaged and this pin can be disengaged from engagement with the locking contour in order to release the movable clutch member.

14. The dog clutch according to claim 13, wherein the activating contour is disposed behind the locking contour in a movement direction of the clutch member when engaging the dog clutch.

15. The dog clutch according to claim 13, wherein the activating contour has an axial distance from the locking contour which corresponds to an axial distance of the teeth of the dog clutch in the disengaged state.

16. The dog clutch according to claim 15, wherein the activating contour has an axial length corresponding to a height of the teeth.

17. The dog clutch according to claim 10, further comprising an evaluation circuit with an A/D component connected to the sensor.

18. The dog clutch according to claim 10, wherein the positioning device includes a compression spring, which presses the movable clutch member into engagement with the other clutch member for the engaging of the dog clutch.

Description

[0018] In the following, the invention shall be explained more closely with the aid of an exemplary embodiment shown in the drawing.

[0019] FIG. 1 shows a schematic partially sectional side view of a dog clutch according to the invention in the disengaged state;

[0020] FIG. 2 shows a corresponding view of the dog clutch in the engaged state;

[0021] FIG. 3 shows an enlarged view of feature III in FIG. 1;

[0022] FIG. 4 shows an enlarged view of feature IV in FIG. 2;

[0023] FIG. 5 shows a current/time diagram.

[0024] The dog clutch 1 shown schematically in the drawing serves to join together in torque-resistant manner a first shaft 2 and a second shaft 3 with aligned axis of rotation 4 in a drive train of a motor vehicle with a disconnectable all-wheel drive for driving in all-wheel mode, and otherwise to separate them from each other. For example, the shaft 2 is the driving shaft and the shaft 3 is the driven shaft, being driven by the shaft 2 when the clutch 1 is engaged or closed.

[0025] The dog clutch 1 comprises a first clutch member 5, which is connected to the first shaft 2 in torque-resistant manner and unable to move in the axial direction of the axis of rotation 4, as well as a second movable clutch member 6, which is connected in torque-resistant manner to the second shaft 3 and able to move on the shaft 3 in the axial direction of the axis of rotation 4.

[0026] The two clutch members 5, 6 are generally designed coaxial to the shafts 2, 3 and each of them comprises a hub part 7 or 8, serving for the connection to the shaft 2 or 3, as well as a radially outer annular clutch part 9 or 10.

[0027] The hub part 7 of the first clutch member 5 is connected in torque-resistant manner to the first shaft 2. For this purpose, the shaft 2 is provided with a groove 11, into which there extends a spring (not shown), projecting beyond the inner circumference of a shaft bore of the clutch member 5.

[0028] Between the hub part 8 of the second clutch member 6 and the second shaft 3 there is situated a bushing 13 provided with an axial external toothing 12, being connected in torque-resistant manner to the second shaft 3 and unable to move axially in relation to the shaft 3. The external toothing 12 of the bushing 13 stands in tooth engagement with a complementary internal toothing 14 on the inner circumference of the hub part 8 of the second clutch member 6, so that the second clutch member 6 can move axially in relation to the bushing 13 and the second shaft 3.

[0029] The two clutch parts 9, 10 are provided with complementary tooth systems 15, 16 at their mutually facing end surfaces. The tooth systems 15, 16 are composed of a plurality of teeth 17 and tooth gaps 18, which may be designed alternating and symmetrical or nonsymmetrical in the circumferential direction of the clutch parts 9, 10. The tooth systems 15, 16 are in form-fitting engagement when the clutch 1 is engaged or closed (FIG. 2), the teeth 17 of the first clutch member 5 projecting entirely into the tooth gaps 18 of the second clutch member 6, the teeth 17 of the second clutch member 6 projecting entirely into the tooth gaps 18 of the first clutch member 5, and both tooth flanks 19, 20 of the teeth 17 lying against the oppositely situated boundaries of the tooth gaps 18. The tooth flanks 19 pointing in the direction of rotation of the teeth 17 of the first clutch member 5 on the drive shaft 2 and the oppositely situated boundaries of the tooth gaps 18 of the second clutch member 6 on the driven shaft 3 are generally oriented perpendicular to the direction of rotation, while the other tooth flanks 20 of the teeth 17 of the first clutch member 5 and the oppositely situated boundaries of the tooth gaps 18 of the second clutch member 6 are slanted in order to make it easier for the teeth 17 to engage in the tooth gaps 18.

[0030] For disengaging or opening the dog clutch 1 there is used a positioning element (not shown) of a hydraulically activated positioning device, or one operated by a spindle drive, for example, which acts on the movable second clutch member 6 in order to move it into the disengaged position, in which the top ends of the teeth 17 of the two tooth systems 15, 16 have a small axial distance A from each other, as shown in FIG. 1.

[0031] For the engaging or closing of the clutch 1, a return spring is arranged between the bushing 13 and the second clutch member 6 in the form of a helical compression spring 21, which, on the one hand, bears against the bushing 13 in stationary manner and, on the other hand, against the movable clutch member 6. The spring 21 is tensioned when the clutch member 6 is moved away from the clutch member 5 by the positioning element upon disengaging or opening the clutch 1.

[0032] In order to hold the second clutch member 6 in the disengaged or opened position, a locking mechanism 22 is provided, comprising an electromagnetic actuator/sensor 23 with a coil 24 and an armature 25 as well as a pin 26 projecting in a prolongation of the armature 25 beyond the actuator/sensor 23 and being rigidly connected to the armature 25. In actuator operation, a voltage is applied to the coil 24 in order to move the armature 25 forward or backward in the coil 24 and thereby move the pin 26 in or out. In sensor operation, a voltage is induced in the coil 24 when the armature 25 is moved forward or backward inside the coil 24 by a force exerted on the pin 26.

[0033] Opposite the actuator/sensor 23, the second clutch member 6 is provided on the outer circumference of the clutch part 10 with a locking contour 27 and with an activating contour 28, which cooperate with the pin 26 of the actuator/sensor 23 situated along the movement path of the second clutch member 6.

[0034] As is best shown in FIG. 4, the locking contour 27 is composed substantially of a groove 29, which is provided at its end away from the first clutch member 5 with a step 30 oriented parallel to the movement direction of the pin 26. When the clutch 1 is disengaged or opened, the step 30 is pressed by the spring 21 against the previously extended pin 26, as shown in FIG. 1. In this position, the pin 26 holds the clutch member 6 firmly in the disengaged state and prevents the engaging or closing of the clutch 1.

[0035] When an unlocking voltage is applied to the coil 24 of the actuator/sensor 23, moving the armature 25 away from the clutch 1, the pin 26 is retracted, whereupon it moves out from the groove 29 of the locking contour 27 and releases the clutch member 6, which is then pressed by the spring 21 in the direction of the first clutch member 5.

[0036] If in this state the teeth 17 of the clutch member 6 stand opposite the tooth gaps 18 of the clutch member 5, and vice versa, as shown in FIG. 1, the clutch member 6 is moved by the spring 21 until the teeth 17 of the two clutch members 5, 6 engage entirely in the tooth gaps 18 of the other clutch member 6, 5, as shown in FIG. 2. In this way, a proper form-fitting connection is produced between the two clutch members 5, 6.

[0037] The activating contour 28 has a rising flank 31, facing the first clutch member 5, which begins at a distance A behind the step 30 on the outer circumference of the clutch member 6 in the movement direction of the clutch member 6 when the clutch 1 is engaged. The gradient of the flank 31, for example, increases gradually and then decreases again. The distance A corresponds to the axial distance between the tops of the teeth 17 of the two clutch members 5, 6 when the clutch 1 is disengaged or opened (FIG. 1), so that the rising flank 31 only moves underneath the partly extended pin 26 in the axial direction if the tooth systems 9, 10 of the two clutch members 5, 6 are engaging with each other. The length L of the activating contour 28 corresponds to the height of the teeth 17. While the activating contour 28 is moving underneath the pin 26 in the direction of the first clutch member 5, it exerts a force on the pin 26, which moves the armature 25 inside the coil 24 away from the dog clutch 1, as shown in FIG. 4. Thanks to this displacement of the armature 25, a voltage is induced in the coil, which causes a current to flow through the coil 24, as indicated in FIG. 5. The voltage induced in the coil 24 and/or the current flowing through the coil 24 are measured and evaluated by an evaluation circuit (not shown), connected to the coil 24, which contains an A/D component and generates a trigger signal when the voltage or the current exceeds a predetermined threshold value S, indicating a proper closing of the clutch 1.

[0038] On the other hand, if the teeth 17 of the first clutch member 5 are standing opposite the teeth 17 of the second clutch member 6 in a “tooth on tooth” position, the teeth 17 of the second clutch member 6 will be pressed by the spring 21 frictionally against the teeth 17 of the first clutch member 5. In this case, the activating contour 28 does not move underneath the pin 26, so that the armature 25 is not displaced inside the coil 24 and no voltage is induced in the coil 24, and no current flows. Therefore, the evaluation circuit does not generate any trigger signal. This means that the clutch 1 is not properly engaged or closed.